It appears on the bootleg Anthology Plus (disc 2). But it certainly isn't The Beatles. From what I've found on the internet, the general conclusion is that it's a group called Mortimer, but it seems no one really knows the answer.

Interesting, Daniel. It's a shame that the waters of Beatles lore get muddied by convincing looking YouTube videos but I guess this sort of thing has been going on for a long time. I'm glad you brought this up.